The use of voice over internet protocol (VoIP) in telephony is growing as the benefits of doing so are becoming more recognized and as suitable telecom equipment becomes available. Initially VoIP was typically used within the telecom network with the call terminations being implemented using traditional analogue and digital telephony technologies. Now, more call terminals (e.g. handsets) are VoIP capable with IP packets originating and terminating directly in the terminal itself.
Similarly, a number of short-range, relatively low-power wireless data protocols have been specified and the equipment needed to implement them have become available and affordable. These include many variants of IEEE 802.11 (also known as Wi-Fi®), IEEE 802.16 (also known as WiMAX™), Bluetooth® and other similar wireless data protocols.
Combining one of the above wireless data protocols with a VoIP terminal results in a VoIP cordless telephone that can be used in a coverage zone (cell) supported by a wireless base-station for that wireless data protocol. Communications between the VoIP cordless telephone and the wireless base-station take the form of IP packages. The base-station can interface with other conventional IP capable devices (e.g. a DSL modem, cable modem) in order to connect to a VoIP gateway and ultimately to a telephony network (e.g. a public switched telephony network (PSTN)) for placing and receiving calls. As the VoIP cordless telephone moves in and beyond the wireless base-station cell, the quality of the telephony transmission can degrade and the connection can be lost due to diminishing signal strength, interference, obstacles and other similar factors.
Degradation of the quality of the telephony transmission can also be caused by factors affecting the IP infrastructure directly such as, for example, traffic congestion in the IP infrastructure (e.g. the IP network), equipment degradation and failures in the IP infrastructure, and other similar sources of degradation. Therefore, telephony transmission quality degradation and loss of connection can affect not only VoIP cordless telephones but also other types of VoIP terminal devices.
What is needed are an apparatus and a method for VoIP call continuity that mitigates the effect of the above described sources of telephony transmission quality degradation and loss of connectivity.